bivy vs camp out

bivy

verb
  • To camp in a bivouac. 

noun
  • A bivouac sack. 

camp out

verb
  • To sleep outdoors, often in a tent. 

  • To wait or queue for something expected to occur, often overnight. 

How often have the words bivy and camp out occurred in a corpus of books? (source: Google Ngram Viewer )